WEBVTT - How Nuclear Weapons Work 0:00:00.320 --> 0:00:02.880 Brought to you by the reinvented two thousand twelve camera. 0:00:03.200 --> 0:00:08.960 It's ready, Are you did? In touch with technology? With 0:00:09.039 --> 0:00:17.760 tech Stuff from how stuff works dot com. Hello again, everyone, 0:00:17.760 --> 0:00:20.000 and welcome to tech Stuff. My name is Chris Polette, 0:00:20.000 --> 0:00:21.919 and I am an editor at how stuff works dot Com. 0:00:22.120 --> 0:00:24.479 Sitting across from me, as he typically does on days 0:00:24.520 --> 0:00:26.200 like this, not rainy ones, but the days we do 0:00:26.280 --> 0:00:30.000 the podcast. Although today's both senior writer Jonathan Strickland of 0:00:30.120 --> 0:00:33.040 Herbert West who was my friend in college, and an 0:00:33.040 --> 0:00:38.120 afterlife I can speak only with extreme terror. Oh that's 0:00:38.120 --> 0:00:40.840 a good one to start today. Yes, today we wanted 0:00:40.880 --> 0:00:44.960 to talk about a subject that is, uh, it's pretty terrifying. 0:00:44.960 --> 0:00:48.960 We're talking about nuclear weapons. Yes, yes, not clear not 0:00:49.200 --> 0:00:53.280 nuclear he was. I was teasing him about this before 0:00:53.320 --> 0:00:55.560 and he said that I had better not I'm not 0:00:55.560 --> 0:00:58.800 gonna say nuclear, I mean other than just then. Um. 0:00:58.840 --> 0:01:00.960 And one of the reasons I wanted to uh to 0:01:01.040 --> 0:01:03.000 talk about this today is because it's been in the 0:01:03.000 --> 0:01:06.679 news a lot lately. Um. Of course, uh iran um 0:01:06.880 --> 0:01:10.600 is rumored or depending on whom you ask, more than 0:01:10.680 --> 0:01:14.880 rumored to be working on nuclear weapons program. And um, 0:01:14.920 --> 0:01:17.880 you know that that's been a busy topic. I was 0:01:17.880 --> 0:01:19.520 about to say, a hot topic, let's not go there 0:01:20.000 --> 0:01:22.480 um lately, and I thought, well, you know, why don't 0:01:22.480 --> 0:01:25.679 we We've never really talked about, um, the technology that 0:01:25.800 --> 0:01:32.040 makes nuclear weapons possible. UM. And while I'm not particularly 0:01:32.080 --> 0:01:37.160 fond of things that cause death and destruction, uh, the 0:01:37.160 --> 0:01:39.840 the actual bombs themselves, how they make them work is 0:01:39.959 --> 0:01:42.840 kind of interesting, and it's it's important stuff. I mean, 0:01:42.920 --> 0:01:44.240 you know, there's a lot of there are a lot 0:01:44.280 --> 0:01:48.240 of discussions about nuclear arms races. You know, we had 0:01:48.840 --> 0:01:51.640 a famous nuclear arms race between the Soviet Union and 0:01:51.680 --> 0:01:56.480 the United States during the Cold War, which uh started 0:01:56.520 --> 0:01:59.400 to look like things were going to to improve, where 0:01:59.560 --> 0:02:02.760 you know, both nations were starting to dismantle a lot 0:02:02.840 --> 0:02:06.320 of their nuclear weapon programs. But then you've got other 0:02:06.400 --> 0:02:11.040 countries like China and India and Pakistan and other countries 0:02:11.080 --> 0:02:14.079 that are that have either have a nuclear weapons program 0:02:14.120 --> 0:02:17.720 or developing. North Korea is another good example. They either 0:02:17.840 --> 0:02:21.600 have a and a fully fledged out nuclear weapons program 0:02:21.680 --> 0:02:24.720 or they're working on it. And uh, it adds a 0:02:24.720 --> 0:02:28.800 lot of concern because these weapons potentially pack an enormous 0:02:28.840 --> 0:02:32.880 punch and it's the kind of weapon that you know, 0:02:33.000 --> 0:02:36.280 most weapons, you use them and then the uh, that 0:02:36.400 --> 0:02:40.000 immediate moment, the aftermath, that's that's all you're dealing with. 0:02:40.080 --> 0:02:43.960 And the aftermath is generally, you know, not not uh 0:02:44.080 --> 0:02:46.920 something that is perpetual, right, I mean, you might have 0:02:47.000 --> 0:02:49.240 to do some massive clean up or whatever, but that's it. 0:02:49.639 --> 0:02:53.760 Nuclear weapons are different, and that the aftermath can be 0:02:53.960 --> 0:02:58.720 as destructive or maybe not as destructive, but but destructive 0:02:58.840 --> 0:03:03.920 on their own beyond the initial blast. And so plus 0:03:03.919 --> 0:03:07.520 plus it's possible that the uh, the effects of the 0:03:07.639 --> 0:03:13.959 nuclear blast can carry across the terrain to places that 0:03:14.320 --> 0:03:18.080 the US, as we'll find out in in our discussion, um, 0:03:18.120 --> 0:03:22.119 that people may not necessarily have been planning on being affected. 0:03:22.240 --> 0:03:24.960 Yeah you might. You know, it's not just the immediate area. 0:03:25.240 --> 0:03:28.480 It's not a precision weapon and that Yeah, there's a 0:03:28.480 --> 0:03:32.080 precision blast area that you're that you can be pretty 0:03:32.120 --> 0:03:34.200 sure is going to be vaporized when you hit it. 0:03:34.560 --> 0:03:37.600 But then there's a large area around that. Depending upon 0:03:37.720 --> 0:03:41.000 the climate and you know, the specific weather conditions at 0:03:41.000 --> 0:03:45.720 that time, it could affect neighboring countries, you know, essentially 0:03:45.800 --> 0:03:49.040 innocent bystanders to whatever. So let's get into this, let's 0:03:49.080 --> 0:03:53.360 talk first about atoms. Yeah, I mean you think about 0:03:53.400 --> 0:03:55.760 it that One of the fascinating things about this is 0:03:56.080 --> 0:04:01.320 that such a devastating reaction can be caused something as 0:04:01.360 --> 0:04:04.760 tiny as an atom. Yeah. Uh. And just so that 0:04:04.800 --> 0:04:07.600 we all have our little a little refresher course, even 0:04:07.600 --> 0:04:10.920 though I'm sure no one listening needs it. Your basic 0:04:11.040 --> 0:04:16.240 atom has a nucleus that is orbited by electrons. Now 0:04:16.279 --> 0:04:19.760 your electrons are you're negatively charged particles. Yes, your nucleus 0:04:20.200 --> 0:04:23.760 typically contains at least one proton. Actually it has to 0:04:23.880 --> 0:04:26.960 otherwise it's not an atom. So the proton is a 0:04:27.000 --> 0:04:30.839 positively charged particle, and the protons positive charge in the 0:04:30.880 --> 0:04:36.080 electrons negative charge are attracted to one another. It's pretty powerful. Now, 0:04:36.160 --> 0:04:42.080 there can also be in that nucleus a and a 0:04:42.080 --> 0:04:46.040 particle that carries no charge at all, a neutron which 0:04:46.080 --> 0:04:49.520 has no charge, and neutrons kind of act like glue 0:04:49.800 --> 0:04:53.840 for protons. Because you know, you've got this this nucleus 0:04:53.920 --> 0:04:56.200 that could have more than one proton. Well, the problem 0:04:56.200 --> 0:05:00.480 is that a similar charges repel one another. So if 0:05:00.520 --> 0:05:02.839 you have to possibly charged particles and you try and 0:05:02.880 --> 0:05:04.800 put them close to each other, they're going to start 0:05:04.800 --> 0:05:07.640 repelling each other. Well, neutrons kind of act like a 0:05:07.720 --> 0:05:11.680 glue that that allows these protons to group together to 0:05:11.760 --> 0:05:16.920 form this nucleus. So, uh, if you've I'm getting out 0:05:16.920 --> 0:05:18.520 of here. No, no, no, no, it's all right, it's 0:05:18.560 --> 0:05:22.839 all right. Now you can change the number of neutrons 0:05:23.000 --> 0:05:26.320 that are within an atom. And if you do that, uh, 0:05:26.560 --> 0:05:29.919 you know, atoms have typically they have a number of 0:05:29.920 --> 0:05:33.599 neutrons that you will naturally find within the atoms of 0:05:33.640 --> 0:05:37.440 that element. Uh. If you find something that's outside of 0:05:37.480 --> 0:05:41.719 that that either is gut either has more fewer neutrons, 0:05:41.800 --> 0:05:46.600 it's an isotope. So isotopes of atoms are atoms that 0:05:46.880 --> 0:05:49.839 contain a different number of neutrons than you would typically 0:05:49.880 --> 0:05:54.800 find them in nature. Plus baseball team in Springfield, that's 0:05:54.800 --> 0:05:59.120 also true. Now, this is not to be confused with ions. 0:05:59.760 --> 0:06:02.560 And ion is an atom that has either gained or 0:06:02.600 --> 0:06:05.520 lost in electron, and so it either has a positive 0:06:05.560 --> 0:06:10.200 charge or a negative charge because of that. So of course, 0:06:10.200 --> 0:06:13.040 if it's gained an electron, then overall the atom has 0:06:13.080 --> 0:06:15.239 a negative charge. If it's lost in electron, then overall 0:06:15.279 --> 0:06:18.440 the atom has a positive charge. So that's the difference 0:06:18.440 --> 0:06:22.600 between ions and isotopes. Now isotopes. Really that's what ends 0:06:22.680 --> 0:06:26.800 up being important in these nuclear weapons. It's it's sort 0:06:26.800 --> 0:06:30.480 of a key feature. Um. Another thing that's that's important 0:06:30.520 --> 0:06:33.000 to note is that for the most part, atoms are 0:06:33.520 --> 0:06:35.800 pretty stable. I mean, once you get them in their 0:06:35.880 --> 0:06:39.800 natural state, they're unlikely to change all that much. They 0:06:39.839 --> 0:06:43.920 don't uh, randomly shed electrons or the things unless some 0:06:44.080 --> 0:06:46.040 force acts on them. They just sort of go along 0:06:46.120 --> 0:06:49.920 there about their business and stick to themselves, right because 0:06:50.080 --> 0:06:52.960 if they were if they were unstable, they would very 0:06:53.000 --> 0:06:56.280 they would not necessarily very quickly. But if they were unstable, 0:06:56.320 --> 0:07:00.159 they would change to become more stable over time. That's 0:07:00.200 --> 0:07:04.000 what we call decay. So if you have an atom 0:07:04.120 --> 0:07:08.560 that is unstable, it will eventually change to a more 0:07:08.600 --> 0:07:10.880 stable form, and in the process of that, it's going 0:07:10.920 --> 0:07:14.040 to give up some energy, uh, and it can give 0:07:14.120 --> 0:07:18.080 up energy and in multiple ways. There's actually three main 0:07:18.200 --> 0:07:24.280 types of radioactive decay. There's alpha decay, which is where 0:07:24.360 --> 0:07:27.200 you've got your nucleus and it it's going to kick 0:07:27.240 --> 0:07:30.640 out two protons and two neutrons bound together, which is 0:07:30.680 --> 0:07:34.720 also called an alpha particle. Then you've got beta decay, 0:07:35.600 --> 0:07:41.560 and this is where a neutron actually changes becomes a proton. Uh. 0:07:41.720 --> 0:07:45.120 Then the neutron or the proton and the an electron 0:07:45.160 --> 0:07:49.360 and an anti anti neutrino are all ejected together. That's 0:07:49.440 --> 0:07:52.160 the beta particle or actually the ejected electron is the 0:07:52.160 --> 0:07:56.600 beta particle specifically UM. So yeah, good all anti neutrinos. 0:07:57.360 --> 0:08:00.280 I tell you they they go opposite the best as 0:08:00.400 --> 0:08:02.840 the speed of light. So we talked about the whole 0:08:02.880 --> 0:08:04.880 new trinos whether or not they were going faster than 0:08:04.920 --> 0:08:06.760 the speed of light with large hatron collider. Right now, 0:08:06.800 --> 0:08:09.160 it looks like they didn't. Looks like that was all 0:08:09.240 --> 0:08:15.000 due to some some issues with the measuring technology. Looking 0:08:15.040 --> 0:08:18.160 at the scoreboard today right, which could change by the 0:08:18.160 --> 0:08:20.880 time this podcast gets out. So the third type is 0:08:20.920 --> 0:08:25.880 spontaneous fission. Now, fission is where you have a nucleus 0:08:25.920 --> 0:08:30.960 split into two pieces. It's um the opposite of fusion. 0:08:31.080 --> 0:08:35.000 Fusion is where two nucleuses come together and join, and 0:08:35.320 --> 0:08:39.360 both vision and fusion you have a release of energy. Now, 0:08:39.559 --> 0:08:43.440 for radioactive decay, we're specifically talking about fission, not fusion. 0:08:44.400 --> 0:08:48.360 So in this the nucleus splits and it might eject 0:08:48.440 --> 0:08:52.839 neutrons which can become neutron rays, and it also can 0:08:52.880 --> 0:08:59.280 emit electromagnetic energy called gamma rays, which do not talk 0:08:59.320 --> 0:09:03.200 about fantast stick for you're looking at me like I 0:09:03.360 --> 0:09:06.960 was talking about some or the Hulk. I was waiting 0:09:07.000 --> 0:09:08.880 for you to make that joke. Actually, I think it 0:09:08.960 --> 0:09:11.640 was cosmic rays with the fantastic gamma radiation for the 0:09:11.679 --> 0:09:14.800 incredible Hulk. I don't want to get my science wrong. 0:09:15.520 --> 0:09:20.560 You're absolutely scientific. My air quotes science wrong. So yeah, 0:09:20.559 --> 0:09:23.679 gamma rays. It's interesting that they are the only type 0:09:23.679 --> 0:09:27.920 of nuclear radiation that comes from energy rather than particles. Yes, 0:09:28.120 --> 0:09:30.240 all right, I bet you learned that on how stuff 0:09:30.280 --> 0:09:32.320 Works dot com. Yes, there's a really good article about that. 0:09:32.400 --> 0:09:34.160 We we have we have a couple of articles on 0:09:34.200 --> 0:09:36.120 how stuff works dot Com that are going to be 0:09:36.160 --> 0:09:38.719 really useful as we talk about this. They include how 0:09:38.840 --> 0:09:43.880 nuclear weapons work, how nuclear how nuclear radiation works, and 0:09:43.920 --> 0:09:47.600 also how there's an article about the Manhattan Project. We'll 0:09:47.600 --> 0:09:51.080 talk about the Manhattan Project in a little bit. So 0:09:51.280 --> 0:09:53.960 we've now got these three different forms of radioactive decay 0:09:54.080 --> 0:09:57.920 and we know about this new spontaneous fission. Well, what's 0:09:57.960 --> 0:10:00.520 interesting is that the fission doesn't necessary really have to 0:10:00.559 --> 0:10:05.360 be spontaneous. If you find the right kind of unstable 0:10:05.480 --> 0:10:10.439 atom and you are able to bombard it with neutrons. 0:10:11.080 --> 0:10:14.920 Then sometimes those atoms will accept a neutron and in 0:10:14.960 --> 0:10:18.000 the process they will become so unstable as that the 0:10:18.080 --> 0:10:21.040 nucleus itself will split apart, and in that process the 0:10:21.120 --> 0:10:24.439 nucleus will release energy. It also may release other neutrons, 0:10:24.760 --> 0:10:26.360 which means that if you get a bunch of these 0:10:26.400 --> 0:10:30.720 unstable items together and you shoot a neutron at them, 0:10:30.760 --> 0:10:34.520 and then that first that first nucleus splits apart and 0:10:34.600 --> 0:10:38.080 more neutrons split off of it, it can cause more 0:10:38.760 --> 0:10:41.320 of these unstable atoms to do the same thing, and 0:10:41.360 --> 0:10:44.280 that's where you have a chain reaction. I can't remember 0:10:44.280 --> 0:10:47.199 who it was that had that the TV show where 0:10:47.600 --> 0:10:51.320 they had a clear plastic box and on the bottom 0:10:51.360 --> 0:10:54.760 of the box they had uh mouse traps, and each 0:10:54.800 --> 0:10:57.400 mouse traps, each mouse trap had two ping pong balls 0:10:57.400 --> 0:11:00.240 on it, and those represented um the stable. Actually, it's 0:11:00.240 --> 0:11:03.400 probably been done by five thousand people anyway. You can 0:11:03.440 --> 0:11:07.400 find clips of the same sort of thing on YouTube 0:11:07.559 --> 0:11:09.720 and then by lots of different people, and I enjoy 0:11:09.760 --> 0:11:13.000 watching it because it's really an excellent demonstration. So each 0:11:13.040 --> 0:11:16.520 of these these mouse trap atoms with its two ping 0:11:16.559 --> 0:11:20.480 pong balls represents these unstable atoms, and as soon and 0:11:20.720 --> 0:11:24.880 the ping pong balls represent the ejected neutrons exactly exactly, 0:11:24.920 --> 0:11:28.280 And so uh, somebody else will drop a ping pong 0:11:28.320 --> 0:11:32.240 ball inside a small hole in the box representing the 0:11:32.240 --> 0:11:35.000 neutron in this case that is bombarding these these atoms. 0:11:35.160 --> 0:11:37.200 And as soon as it hits one mouse trap and 0:11:37.240 --> 0:11:39.920 sets it off, the ping pong balls from that one 0:11:40.080 --> 0:11:43.760 fly in other directions, thereby setting off the other mouse traps, 0:11:43.960 --> 0:11:45.920 and it all happens in a very very short period 0:11:45.920 --> 0:11:47.400 of time. It takes almost no time at all for 0:11:47.440 --> 0:11:50.120 this thing, for all the the mouse traps to release 0:11:50.120 --> 0:11:52.960 their part of ping pong balls now. And in the 0:11:52.960 --> 0:11:55.679 case of a nuclear weapon, these reactions are happening in 0:11:55.800 --> 0:12:00.440 billions of a second. So now let's get to the 0:12:00.480 --> 0:12:04.160 actual elements that are used in nuclear weaponry. So one 0:12:04.200 --> 0:12:07.720 of them is an isotope of uranium, uranium two thirty five. 0:12:08.040 --> 0:12:12.960 That's a very complex atom. Yeah, it's got ninety two protons, right, so, 0:12:13.280 --> 0:12:16.760 but it's got a hundred and forty three neutrons. And 0:12:16.800 --> 0:12:19.640 the thing about this is that it will accept a 0:12:19.679 --> 0:12:23.400 neutron if if you bombard uranium two thirty five, it 0:12:23.559 --> 0:12:28.080 very easily will accept that neutron. Yeah yeah, and then 0:12:28.320 --> 0:12:31.760 it it makes the uranium unstable, and then it will 0:12:31.800 --> 0:12:34.080 split apart like I just said in and you'll get 0:12:34.080 --> 0:12:40.199 that energy and those other neutrons released. So that the problem, 0:12:40.280 --> 0:12:43.280 the problem with this, many problems with this. One of 0:12:43.280 --> 0:12:46.800 the issues that the people who first started working on 0:12:46.960 --> 0:12:50.840 nuclear weapons technology encountered was that, first of all, they 0:12:50.840 --> 0:12:54.560 weren't sure which elements were going to react this way, 0:12:54.600 --> 0:12:57.520 because not all of them do, so finding the right 0:12:57.559 --> 0:13:01.160 elements was tricky. The other part is that uranium two 0:13:01.160 --> 0:13:07.760 thirty five is relatively rare compared to other isotopes of uranium. Yeah, 0:13:07.760 --> 0:13:11.120 that's right. So when you find naturally occurring uranium, the 0:13:11.600 --> 0:13:15.040 uranium two thirty five in that deposit is going to 0:13:15.080 --> 0:13:20.480 be relatively sparse, and for a nuclear weapon to work, 0:13:20.520 --> 0:13:25.120 you need about uranium two thirty five so that you 0:13:25.240 --> 0:13:30.480 have the right amount of material to perpetuate this chain reaction. 0:13:30.559 --> 0:13:36.319 Otherwise your your atoms that are unstable, maybe too far 0:13:36.400 --> 0:13:39.440 apart from each other for that chain reaction to really 0:13:39.480 --> 0:13:43.720 take off. Note to all the nuclear physicists who are 0:13:43.760 --> 0:13:46.760 writing who have paused to podcast and rode in to 0:13:46.800 --> 0:13:48.920 tell us that there are other types of fuel that 0:13:48.960 --> 0:13:51.040 can be used for nuclear weapons. Yes, we know that. 0:13:51.600 --> 0:13:54.920 However we're using we're starting here, starting with uranium because 0:13:54.920 --> 0:13:58.079 that's where that's where, that's where the scientists started. Yes, 0:13:58.320 --> 0:14:01.440 plutonium also used as all as their hydrogen bombs that 0:14:01.440 --> 0:14:03.679 we'll talk about a little bit. But even hydrogen bombs 0:14:03.760 --> 0:14:08.400 use uranium and plutonium um. It's just that they're they're 0:14:08.480 --> 0:14:11.720 using a different mechanism. They're using fusion as opposed to vision. 0:14:12.240 --> 0:14:16.960 So uranium two thirty five, you have to actually refine 0:14:17.000 --> 0:14:21.400 your your right, your uranium. Wow, I can't talk today, 0:14:21.440 --> 0:14:26.880 but yes, you must take uranium, your uranium, yeah, toy 0:14:26.960 --> 0:14:30.600 boat anyway, you have to take this uranium there we 0:14:30.640 --> 0:14:33.480 got that works and refine it so that you have 0:14:33.840 --> 0:14:36.320 a higher percentage of uranium two thirty five. Which is 0:14:36.600 --> 0:14:38.480 what you hear about when you when you hear about 0:14:38.480 --> 0:14:43.160 these these nations like Iran with their nuclear program, you 0:14:43.240 --> 0:14:48.080 hear about are they making uranium for power facilities or 0:14:48.080 --> 0:14:51.440 are they trying to make weaponized uranium. This is talking 0:14:51.440 --> 0:14:55.640 about the enrichment process. Yes, so if you are enriching, 0:14:56.000 --> 0:14:58.600 if you're if you're creating uranium, so that you've got 0:14:58.960 --> 0:15:04.360 a section of uranium the is uranium that's indicative of 0:15:04.400 --> 0:15:07.120 a weapon that's not. You don't need that kind of 0:15:07.120 --> 0:15:10.280 concentration for a nuclear power facility. So that's one of 0:15:10.280 --> 0:15:14.400 those things that that inspectors try to determine when they 0:15:14.400 --> 0:15:17.360 go and look at a nuclear power facility to make 0:15:17.360 --> 0:15:22.120 sure that the uranium being produced is not weapons grade uranium. 0:15:22.160 --> 0:15:26.720 So anyway, that's the basis, that's the basic science behind 0:15:26.760 --> 0:15:30.680 the fission part of nuclear weapons. Will get into fusion 0:15:30.680 --> 0:15:34.560 in a second. So how did this all come about? Well, 0:15:35.120 --> 0:15:39.000 first we have to look at a fellow named Einstein. Now, 0:15:39.040 --> 0:15:43.480 Einstein came up with that famous equation E equals MC 0:15:43.600 --> 0:15:48.040 squared the theory of relativity, which states that energy is 0:15:48.120 --> 0:15:51.880 equal to mass times the speed of light squared the 0:15:51.960 --> 0:15:54.480 constant of the speed of light through a vacuum. As 0:15:54.480 --> 0:15:57.960 it turns out, so that means that you take the 0:15:58.240 --> 0:16:02.080 you take and a unit of mass, you multiply it 0:16:02.080 --> 0:16:05.240 by the square of the speed of light speed of 0:16:05.280 --> 0:16:09.320 light squared rather and and then that's how much energy 0:16:09.400 --> 0:16:12.440 you get from that mass. So this tells us that 0:16:12.480 --> 0:16:14.760 a tiny little bit of mass could equate to an 0:16:14.880 --> 0:16:17.720 enormous amount of energy because you're multiplying that that unit 0:16:17.720 --> 0:16:23.800 of mass against a huge number. Well, that starts leading 0:16:23.840 --> 0:16:27.320 people to think, well, this is true, then there should 0:16:27.320 --> 0:16:31.120 be some way to tap into the stuff that's around 0:16:31.200 --> 0:16:34.280 us and get at huge amounts of energy. And you 0:16:34.320 --> 0:16:36.840 had a lot of really really smart people working on this, 0:16:37.080 --> 0:16:40.080 and most of them were probably at least initially working 0:16:40.160 --> 0:16:42.400 on this as a way of finding a new energy source, 0:16:43.240 --> 0:16:47.520 not necessarily a weapon. However, World War Two really helped 0:16:47.960 --> 0:16:52.760 push the the the the research towards finding a way 0:16:52.800 --> 0:16:55.640 of using this in a military application as opposed to 0:16:55.640 --> 0:17:03.160 to just a power generation alternative. So then we go 0:17:03.280 --> 0:17:05.560 up to the nineteen thirties. You've got a fellow named 0:17:05.800 --> 0:17:11.960 Enrico Fermi, and hep him in grade school. He's the 0:17:12.000 --> 0:17:16.200 one who discovered that if you were to shoot neutrons 0:17:16.400 --> 0:17:20.600 at atoms, you could sometimes form new elements. And they 0:17:20.600 --> 0:17:23.040 were including ones that just did not show up on 0:17:23.080 --> 0:17:25.960 the periodic table at all. So most of these are 0:17:26.480 --> 0:17:28.720 are atoms that are so unstable that you know they 0:17:28.760 --> 0:17:33.679 almost immediately decay. But uh that he discovered that, and 0:17:33.720 --> 0:17:36.240 then a few years later a pair of German scientists 0:17:36.280 --> 0:17:41.520 Otto Hahn and Fritz Strassman discovered that by bombarding uranium 0:17:41.520 --> 0:17:45.360 with neutrons that they could create cause the uranium atoms 0:17:45.400 --> 0:17:49.440 to split. So they're the ones who actually connected the 0:17:49.480 --> 0:17:56.000 concept of fission with shooting neutrons at an isotope and 0:17:56.160 --> 0:17:59.159 uh it actually created a radioactive barium isotope once they 0:17:59.160 --> 0:18:00.919 did that, and that's how they discovered, oh, you know, 0:18:01.280 --> 0:18:04.239 this is what happens. If you do this, then you 0:18:04.320 --> 0:18:06.880 have a couple of other There are so many famous 0:18:06.960 --> 0:18:09.560 names that we could mention that worked on this, but 0:18:09.960 --> 0:18:14.080 Neil's Bore and John Wheeler started to theorize that if 0:18:14.119 --> 0:18:17.199 you were to create a fission reaction within enough of 0:18:17.240 --> 0:18:21.680 this material, you could cause a chain reaction, and if 0:18:21.720 --> 0:18:24.120 you were to contain this in some way, you could 0:18:24.119 --> 0:18:27.960 have a controlled nuclear reaction which would generate huge amounts 0:18:28.000 --> 0:18:32.760 of energy. Uh. Now, a controlled nuclear reaction could allow 0:18:32.800 --> 0:18:36.560 you to have uh power, or a controlled nuclear reaction 0:18:36.600 --> 0:18:40.720 that then results in an uncontrolled explosion is a weapon. 0:18:40.760 --> 0:18:43.560 It's a bomb. You know. I'm sort of reminded of 0:18:43.560 --> 0:18:47.600 our our discussion of quantum computing, which also works with adams. 0:18:48.520 --> 0:18:51.879 But the thing is that figuring out the predict predictability 0:18:52.000 --> 0:18:55.240 if you happen to listen to that podcast of where 0:18:55.240 --> 0:18:59.080 the particle will go and in what direction um is 0:18:59.119 --> 0:19:00.879 not always possible. That's one of the things that makes 0:19:00.960 --> 0:19:05.320 quantum cryptography so useful. But yeah, in this case, UM, 0:19:05.520 --> 0:19:07.919 it's kind of scary because if you imagine that this 0:19:07.920 --> 0:19:10.560 this reaction is going to unleash a large amount of power, 0:19:11.320 --> 0:19:14.879 or maybe it won't. You know, that's that can be 0:19:14.920 --> 0:19:17.440 a little scary because you don't know for sure exactly 0:19:17.440 --> 0:19:19.199 what's gonna happen when you do this is which is 0:19:19.200 --> 0:19:24.119 why UM, you know, they started doing experiments like you know, 0:19:24.160 --> 0:19:27.720 Columbia University in n um up in New York. They 0:19:28.040 --> 0:19:29.639 starting to mess around with this to see if they 0:19:29.640 --> 0:19:33.640 could make it work. University of Chicago squash court. Yes, yes, 0:19:33.640 --> 0:19:38.760 now that's funny because of underground underneath the famous stag 0:19:38.840 --> 0:19:41.640 field there at the University of Chicago. UM, they were 0:19:42.000 --> 0:19:46.880 Enrico Fermi finally got it to work in the controlled situation. UM, 0:19:46.960 --> 0:19:50.760 so you know, again, what what if it weren't controlled 0:19:50.880 --> 0:19:53.399 that might have been a little scary, but uh, you know, 0:19:54.160 --> 0:19:55.879 he got it to to uh to do what they 0:19:55.960 --> 0:19:58.639 thought and this This was important because UM again this 0:19:58.720 --> 0:20:02.520 is they realize is that this could be a seriously 0:20:02.720 --> 0:20:07.160 potent weapon that they could be building. So UM they 0:20:07.200 --> 0:20:09.119 realized that if they could harness this and do this 0:20:09.200 --> 0:20:11.679 in a controlled way, you know, then they could turn 0:20:11.720 --> 0:20:14.960 it to their advantage. UM. Around the same time that 0:20:15.920 --> 0:20:21.719 work was being done on uranium uh and and nuclear fission, 0:20:22.160 --> 0:20:25.680 scientists over at the University of California at Berkeley back 0:20:25.720 --> 0:20:32.720 in discovered a new element, element ninety four uh and 0:20:32.760 --> 0:20:36.400 They thought that this could also work as a potential 0:20:36.520 --> 0:20:41.960 fuel for nuclear chain reactions. And this element they named 0:20:42.119 --> 0:20:47.960 plutonium and the dog, Yes, it was named for the 0:20:48.000 --> 0:20:51.920 dog the it took. It took his name for the 0:20:52.920 --> 0:20:57.400 Roman god. But yeah, it was a year later they 0:20:57.400 --> 0:21:01.560 had actually produced enough plutonium to finally do some experiments 0:21:01.560 --> 0:21:04.159 on it, because it was not something that was easily found, 0:21:04.400 --> 0:21:08.200 which I guess we should all be thankful for. UM. 0:21:08.240 --> 0:21:12.200 And they they figured out that plutonium also would undergo 0:21:12.240 --> 0:21:16.320 fission when bombarded by neutrons. You know, we should talk 0:21:16.320 --> 0:21:21.920 about the criticality of about the of the the atoms themselves. 0:21:22.400 --> 0:21:26.520 Because the thing is, UM say, say you have your 0:21:26.560 --> 0:21:29.199 your creative mousetratchs and ping pong balls. You have to 0:21:29.240 --> 0:21:32.040 make sure that nothing is going to set it off 0:21:32.359 --> 0:21:34.760 before you mean to set it off. Yeah, you don't 0:21:34.800 --> 0:21:39.000 want to have something jostle that that system and have 0:21:39.160 --> 0:21:41.920 it all go off prematurely. And of course with a 0:21:42.000 --> 0:21:45.480 nuclear bomb, this is truly important because of the the 0:21:46.160 --> 0:21:48.720 just the enormous amount of damage that it could it 0:21:48.800 --> 0:21:54.600 could it could cause. So yeah, so there's there's a 0:21:54.600 --> 0:21:57.760 couple different concepts here. There's a concept called critical mass, 0:21:58.800 --> 0:22:03.040 which is the minimum amount of mass necessary for you 0:22:03.119 --> 0:22:07.440 to have a sustain nuclear fission reaction. And then there's 0:22:07.480 --> 0:22:11.560 the subcritical mass, which is where you've got lower than 0:22:11.600 --> 0:22:15.119 that amount, And ideally what you want is to have 0:22:15.320 --> 0:22:17.960 lower than that amount up until the point where you 0:22:18.000 --> 0:22:22.240 actually want to detonate the bomb. Yes, because that's going 0:22:22.280 --> 0:22:25.439 to keep it as safe as you can you can 0:22:25.520 --> 0:22:28.879 get it. So there were a lot of challenges in 0:22:29.119 --> 0:22:32.280 trying to find a way to create a bomb where 0:22:32.520 --> 0:22:37.119 you had the material set up as subcritical until the 0:22:37.200 --> 0:22:40.240 moment of detonation, where it would convert to a critical mass, 0:22:40.280 --> 0:22:43.879 so that that nuclear reaction would remain sustained within it. 0:22:43.920 --> 0:22:47.960 Otherwise your bomb would still be dangerous. It would still 0:22:47.960 --> 0:22:50.720 emit radiation, It would still admit a lot of energy, 0:22:50.760 --> 0:22:54.440 it just wouldn't cause as much damage as it was 0:22:54.520 --> 0:22:57.359 designed to do. Right now, now, critical mass is, as 0:22:57.400 --> 0:23:01.439 Jonathan said, the minimum amount needed to to achieve the 0:23:01.480 --> 0:23:05.520 fish and reaction. Now uh, ideally for a for a 0:23:05.560 --> 0:23:08.639 bomb condition, if you're you're trying to do this, um, 0:23:08.720 --> 0:23:11.040 you would want the fuel to be in a supercritical mass, 0:23:11.200 --> 0:23:14.760 which basically means there's more than enough necessary to to 0:23:14.800 --> 0:23:18.600 achieve the fish and reaction. Um uh you know, because 0:23:20.160 --> 0:23:23.480 in this case it just applies and plenty. You want 0:23:23.480 --> 0:23:26.200 to make sure that it's going to happen. You don't wanna, 0:23:26.400 --> 0:23:29.560 you don't want to have it where through some weird 0:23:29.720 --> 0:23:35.520 set of circumstances, just some improbable but possible outcome that 0:23:35.600 --> 0:23:40.119 the bomb that a smaller percentage of the reactions takes 0:23:40.119 --> 0:23:42.520 place than you had anticipated, because that means that the 0:23:42.560 --> 0:23:45.000 effect is going to be smaller than you had anticipated. 0:23:45.600 --> 0:23:48.159 And if you're gonna be building something as nasty and 0:23:48.280 --> 0:23:50.840 dangerous as a nuclear weapon, you kind of want it 0:23:50.880 --> 0:23:54.600 to be effective. Yes. Yeah, The point is again to 0:23:54.600 --> 0:23:58.199 to operate it when it's going to achieve the desired effect, 0:23:58.240 --> 0:24:00.639 and not before and which is really I mean, this 0:24:00.680 --> 0:24:02.280 is where it gets hard to talk about this because 0:24:02.280 --> 0:24:06.480 the desired effect is so mind numbingly awful. Yeah, I'm 0:24:06.480 --> 0:24:10.960 trying to speak of it in a in a clinical sense. Um. Yeah, 0:24:10.960 --> 0:24:13.440 it's it's a little rough. So there there are two 0:24:13.480 --> 0:24:20.520 different ways to create a supercritical mass within a fission 0:24:20.720 --> 0:24:25.240 based bomb. Uh. And actually both of these ways were 0:24:25.359 --> 0:24:29.600 used in the first two nuclear weapons ever actually used 0:24:29.600 --> 0:24:32.400 in battle. Um. One of the things that I think 0:24:32.400 --> 0:24:35.600 of is uh, again in in a clinical sense, but 0:24:35.640 --> 0:24:38.080 it's it's still kind of amusing to me, is in 0:24:38.119 --> 0:24:42.040